Partly to mostly cloudy conditions obscured views of Cleveland volcano by satellite today. No reports of activity have been received.

Without a real-time seismic network on Cleveland volcano, AVO is unable to detect local earthquake activity related to volcanic unrest and cannot rely on seismic data to forecast possible eruptive activity. Brief explosive bursts in the summit vent may generate ash clouds that could rise more than 20,000 ft. above sea level and drift from the volcano with the prevailing winds. Without a seismic network in place, the only way to detect such ash clouds is to observe them in satellite imagery. Satellite images of Cleveland volcano are acquired about every two hours. Small volume ash emissions occur frequently at Cleveland and do not necessarily mean a larger eruption is imminent. The last ash cloud we detected was on September 12, 2010. Weak thermal anomalies have been regularly observed in the summit crater for the past eight months through February 2011. AVO continues to monitor the volcano using satellite imagery, pilot reports, and local observations made by passing boats.

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.

VOLCANO ALERT LEVELS

NORMALVolcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.

ADVISORYVolcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.

WATCHVolcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.

WARNINGHazardous eruption is imminent, underway, or suspected.

AVIATION COLOR CODES

GREENVolcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.

YELLOWVolcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.

ORANGEVolcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway with no or minor volcanic-ash emissions [ash-plume height specified, if possible].

REDEruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].